Help needed to copy part of a canvas

[fbeleznay]

@Kevinkun

1. you need to improve your drawPattern function, which use drawPoint pixel by pixel, that's too slow, you need to change to use DrawLine to draw small square.

I change the width of the line and this way DrawPoint does draw a small square, not just a pixel.

@Kevinkun

2. You can move imageSprite out of canvas by using extension in post #40.

I will look at that extension.

@Kevinkun

what about the part you move our of the canvas? just discard them?

Yes, for the moment I discard the part that moves out of the screen.

[Kevinkun]

Not tested:

save canvas then set it as background image, will make the image more and more blur.
Maybe try to set background image with Base64, using this extension.

[fbeleznay]

I will try, but the problem is not in which format the image is stored. I can store it as a png, which is a lossless compression. The problem is that the background image is not stored at the resolution of the canvas, so in the storing process itself data is lost.

[Kevinkun]

Since all your pattern is drawn by DrawPoint, you can save all the point location (x,y), to a list. When redraw, loop on this list, draw the point at (x+offsetX, y+offsetY), save this new location also.
Also add the new drawn point to this list.

[ABG]

I propose separating the grid calculations from its rendering.

Help needed to copy part of a canvas

Are you getting a rectangle from each DrawPoint call? If not, a fat DrawLine should give you a redraw speedup. [drawPattern] P.S. I was surprised to learn that the DrawPoint block actually draws a square with size equal to Canvas.LineWidth. So DrawLine would not provide any speedup.

This procedure should emit a table (list of lists) of 1s and 0s for a grid to be fed to a rendering procedure.

Because the grid repeats, it need only be computed once.

The SVG rendering of each row also needs to be done only once.

Linked lists are perfect for cycling through rows of tables.